Retarding chamber



lnvenTor.

Oct. 18, 1932. w. K. HODGMAN, JR

RETARDING CHAMBER Filed Feb. 2, 1929 WiHis K. Hodgmundf. y/04 Patented Oct. 18, 1932 WILLIS .K. noneivmn, an, or raun'romivmsszionusnrrs nn'mnnme CHAMBER Application filed February 2, i929. Serial No. 337 ,102.

. This invention relates to a retarding chamber apparatus for a liquid supplying system under pressure. 7 Such a system is exemplified in the well-known automatic fire sprinkler systems. In such systems it is desirable that an alarm be given whenever the liquid under pressure flows continually under full head for a predetermined period, as, for 6X- ample, within a short predetermined period 10 after a sprinkler has opened. But it is essential also that so far as possible no alarm shall be given with a lesser flow, as, for ex.- ample, when the .flow results from pulsations due to variations in pressure of the supply or from water hammer. It is also desirable that the entire .fiow diverted to operate the alarm shall be avilable for that purpose and that there be no undue waste of water.

It is the object of -the present invention to provide an apparatus which shall answer all the foregoing requirements, which shall be of simpleconstruction and which shall contain no parts liable to get out of order or to become clogged as the result of any impurities in the liquid. 7 I

These and other objects and features of the invention will appear more fully from the ac companying description and drawing and will be particularly pointedout in the claims. The invention is disclosed as embodied in a liquid supplying system under pressure such as that employed in automatic fire sprinkler systems which control the flow of water to and through the sprinklers. As such sys terns are generally well known and familiar, and as the invention is concerned entirely with the apparatus for giving the alarm, it is only necessary here to illustrate and describe those features of such a system and apparatus 40 with which the invention is particularly concerned. Furthermore, as the alarm mechanism itself may beof any desired type or construction, and as such alarm mechanism forms no .part of the present invention, .it is unnecessary to illustrate and describe any such mechanism. ;In an automatic fire sprinkler system, it is usually desirable that,whenever a sprinkler opens and therefore the water begins to flow continuously through the sprinkler, the

a1arm shallbe given within half aminute after the continuous flow begins. It is also desirable that all the water diverted to operate thea'larm shall be utilized for that purpose until the alarm i sgivemand' that'there be no undue Waste of water beyond what is necessary for this purpose. While. water is wasted whenever the flow is sporadic due to changes in'pressure, pulsations in the system, water hammer, etc., such waste isnot large and is practically unavoidable.

In the drawing: I

Fig. l is a more or less diagrammatic view partially in vertical cross section of an apparatus embodying a preferred form of; the presentinvention'. r V p p F ig. 2 is'a' view chiefly in vertical cross section and on a larger scale showing the mouthpiece, nozzle and adjacent parts. V

An alarm valve casing l is shown having an inlet 2 normally connected with the supply of liquid under pressure, such, for example, as a city water system and having an outletf3 normally connected to the sprinkler system from which the water isdischarged, 7 when a fire occurs, through sprinklersin a familiarmanner. This alarm valve casing is shown as provided with an alarm valved pivoted at 5 and held bygravity and bythe difierence in pressures between the water above andflbelo-w the valve on the valve seat 6.: At one side of the casing 1 a-fitting 7 is inserted having an auxiliary valve seat 8 closed, when the valve 4 is seated,by an auxiliary valve 9, carried by an extension of the valve 4.' A pipe 10 extends from the fitting 7 through a shut-off valve ll, through a suit-- ablestrainerl12 and through connections, to

be described, to the, retarding chamber 13.

From the top of the retarding chamber rises a pipe 14. This general arrangement is of a familiar type. The general idea is that whenever a'continuous flow is started in the system, as by a sprinkler opening, the alarm valve dis swung open and a portion of the water flowing passes through the pipe 10,

fills the retarding chzimberl3, passes up the pipe 14 and gives the alarm in any well-' known manner. If, however, some pulsation inthe system occurs, as, for'example, by a I the valved returns to its seat, any water sudden change in pressure of the main supply or otherwise, the alarm valve 4 may open partially and then drop back on its seat,

thus allowing a sporadic flow of water 7 through the pipe lOinto the retarding cham-' her. The retarding chamber is of such a size that sucha flow will not fill the chamber, rise in the pipe 141 and give the alarm, and when 7 mouthpiece may be of any suitable form but preferably is designed on the principle of permitting a free flow otwater from the retarding chamber when the valve 4 returns to its seat and after the water has passed the orifice. The throat, or that section of minimum area 18 at its inner end preferably enters the wall of the retarding chamber at aright angle so as to present 'asharp edge orifice 30. Otherwise, it is found in practice, the discharge flow from the retardingchamber might be too free, From the throat outward, that is, from the retarding chamber the area of the mouthpiece enlarges gradually until it'reaches its maximum area at about 19 which is the end of the mouthpiece proper. WVith such a mouthpiece, if smooth and well formed, the discharge of flow outwardly.

therethrough after passingthe orifice 30 in the wallet the retarding chamber will depend on the area of the mouthpiece at the section 19 and not on the area at-the throat which therefore may be made quite small without afiecting the quantity of discharge. Such a mouthpiece isknown asof the divergent conoidal type and liquid will under. all conditions fiow freely outwardly therethrough. V

' The pipe terminates in a nozzle20 loca ed coaxially of the mouthpiece and having its discharge opening 21 adjacent the end of the mouthpiece proper and the area of the discharge opening 21 of the nozzle is made substantially equal to the area of the throat 18 and, if anything, slightly lessv in area. 1

The-nozzle 20 is shown as threaded at 22 into an outwardly tapering extension 23 of the mouthpiece with a shouldered portion 24 abutting the end of this extension. The pipe 10 is conveniently threaded at 25 into the outer end otthe nozzle.

It is desirable that; after thev divergent connoidal mouthpiece has reached its maxi mum area at 19, that the area of flow through the extension 23 shall not be diminished and the crosssectional area of the space '26 between the nozzle and the extension of the mouthpiece shall nowhere be less than the' maximum area at 19.

A drain opening leadmg from the mouthpiece extension'23 is provided and is herein shown as including a pipe27 threaded into boss 28-at the bottom of the mouthpiece extension 23. The area of this drain opening is conveniently utilized to determine finally the outward flow from the retarding chamber. In the construction illustrated, the wall of the mouthpiece extension 23 j above the'boss 28 is drilled through to form a bore 29 of a diameter found to give the desired result. Under ordinary conditions it has been found that with the diameter ofthe bore 29 equal to the diameter of the nozzle opening 21,

highly satisfactory results are achieved.

- The parts are so correlated by being proportionedand arranged on the'principle thus described that when the liquid flows continuously for a predetermined period under full head, as when a sprinkler opens, past the alarm valve .4 and consequently through the pipe 10, it will issue as a jet from the discharge opening 21 of the nozzle 20 and this jet willcompletely fill the throat 18 of the mouthpiece. Thus the liquid passes into the retarding chamber, fills the retarding chamher, and rises in thepipe 14 to operate the alarm with promptitude. Since the jet fills thethroat 18, there can'be no flowin a reverse direction out from the retarding chamber through the mouthpiece. Thus all the liquid diverted from the main through the nozzle is utilized to operate the alarm. No

waterflows outthrough the pipe 27 and in practiceit is found that a substantial suction is formed at the drain opening. When thealarm is in operation, the resulting back pressure will, of course, result in some outward flow through the drain opening, which is unavoidable.

Ifihowever, the flow through the pipe 10 is a sporadic one dueto a slight opening or vibrationof the alarm valve 4 and is very small, the liquid will run outthrough the nozzle 20, back through the space 26 and out the pipe 27. If larger, a part-0t the flow will 7 pass from the nozzle 21, through the mouthpiece into the retarding chamber 13 and par- '7 tially fill it. But immediately the valve 4 seats, the liquid in the retarding chamber flows rapidly out through the mouthpiece and extension and thence through the pipe 27, so that the retarding ohamberis quickly emptied.

. It will be seen that the construction. is of a simple form, that there are no movable parts and'that there is nothing that can get out of orderor become clogged or rendered inefiectiveby reason of impurities in the liquid. \Vhen the liquid is discharging stead ily from the nozzle 20, as when one or more sprinklers have opened, and consequently the liquid is under full head (the term full head meaning herein such ahead as it is desired shall under the given conditions oper- I will be of substantially constant area for the length of the mouthpiece and at the throat of an area equal thereto. Thus outward flow from the retarding chamber is prevented and all the liquid flowing isrendered available to fill the retarding chamber and operate the alarm.

. While it is preferable that the construction be such as to cause the et, when discharging steadily under full head from the nozzle 20, completely to fill the throat 18 and thus prevent any outward flow whatever, it is evident that substantial advantages may be secured with this lnventlon even when the construction is such that the jet lssomewhat smaller than the orifice so that some outward flow through the orifice around the jet may occur. But, in any event, the invention combines in a single orifice the admission and discharge opening to and from the retarding chamber and the invention thus presents a construction in which the jet controls the discharge from the chamber through the. orifice or throat of the mouthpiece so that the required pressure may be built up in the chamber within a predetermined time. v

It wlll also be seen that any sporadic flowis quickly and freely drained off from the retarding chamber through the mouthpiece, its extension and the drain opening, while the flow of the discharge isreadily controlled under the conditions by the area of the opening 29. a

Thus repeated sporadic flows may take place without building up a sufiicient pressure in the retardmg'chamberto operate the alarm unless conditions are reached equivalent to a continuous flow under full head-for the predetermined period. The invention therefore, when applied to sprinkler system, for example, insures the desired prompt axially' of the mouthpiece with 1 its discharge opening'adjacent the greatest'area of the mouthpiece"and1with the area of its discharge opening substantially equal to the areaof the throat of the mouthpiece and adrain openingleading from the-mouthpiece correlatedftocause a continuous flow for a predetermined period through the nozzle under'full'head to produce a jetfillin'gthe throat'of the mouthpiece thus filling the retarding chamber and preventing outward flow from the chamber and to'cause sporadic through'the drain opening or partially to fill the retarding chamber and flow outward quickly and freely therefrom through the drain opening. 4

2. A retarding chamber having the cone,

1 flows] through the nozzle toflow outward struction defined in 'claim 1,- in which the" mouthpiece is provided with an extension outward'surroundin the nozzle and presenting an area'between itself and the nozzlenot less than the maximum connoidal area of the mouthpiece, inwhich the drain opening extends from the area between the mouthpiece extension and the nozzle and in which the area of the drain opening determines the outward flow from theretarding chamber. 7

3.:A retarding chamber having the construction defined in claim 1, in. which the connoidal mouthpiece presents no abrupt change in area so that there'is no abrupt change in velocity ofliquid flowing outward therethrongh from the'retarding chamber.

A. A retarding chamber having the eon: struction defined in claim 1 in which the end of the mouthpiece between the retarding chamber andthe throat has the form approx{ imately of a simple contracted vein and'in which the mouthpiece from the throat outward enlarges gradually. to an area unrestrictive of the quantityof discharge when liquid is flowing freely from the retarding chamber, and in which the discharge area from the end ofthe mouthpiece on out through the drain opening determines the outward .flow from the retarding chamber.v I

. 5; A retarding chamber for a liquid supplying system underpressure, in which the said chamber is closed except for an alarmoperating connection and for a'single' orifice acting both to admit liquid to, and discharge I operate the alarm is builtup in the chamber by the liquid.

6. A retarding chamber for a liquid supplying system under pressure in which the said chamber is closed except for an alarm-operat-ing connection and for a single mouthpiece through which liquid is both admitted to, and discharged from, the chamber, a drain opening leading from the mouthpiece, and a nozzle connected to the supply system and located coaxially of the mouthpiece and constructed and arranged to produce,: when the flow through the nozzle is continuous for a predetermined period under full head, a jet filling the throat of the mouthpiece flowing through V the mouthpiece into the chamber and preventing discharge from the chamber through the mouthpiece until the pressure required to operate the alarm is built up in the chamber 15 by the liquid. a

7. A retarding chamber for a liquid supplying system under pressure in which the said chamber is closed except for an alarmoperating connection and for a single orifice CO acting bot-h to admit liquid to, and discharge liquid from, the chamber, and a nozzle connected to the supply system located opposite said orifice and constructed and arranged to produce, when the flow through the nozzle is continuous for a predetermined period under full head, a jet flowing through the orifice into the chamber and controlling the discharge from the chamber through the orifice to cause the pressure required to operate the alarm to be built up in the chamber by the liquid within-a predetermined time. 7

8. A retarding chamber for a liquid supplying system under pressure in which the said chamber is closed except for an alarm- 35- operating connection and for a single mouthpiece through which liquid is both admitted to, and discharged from, the chamber, adrain opening leading from the mouthpiece, and a nozzle connected to the sup-ply system and 40- located coaXially of the mouthpiece and constructed and arranged to produce, when the flow through the nozzle is continuous for a predetermined period under full head, a jet flowing through the throat of the mouthpiece 215: into the chamber and controlling the dis-v charge from'the chamber through said throat to cause the pressure required to operate the alarm to be built up in the chamber within a predetermined time.

In testimony whereoflI have signed my name to this specification. V

WILLIS HODGMAN, JR. 

